A Force from Empty Space: The Casimir Effect
2.01.2010

This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to energy fluctuations in the vacuum of empty space.

NGC 3314: When Galaxies Overlap
16.11.2021

Why doesn't the nearby galaxy create a gravitational lensing effect on the background galaxy? It does, but since both galaxies are so nearby, the angular shift is much smaller than the angular sizes of the galaxies themselves.

Tunguska: The Largest Recent Impact Event
2.10.2011

Yes, but can your meteor do this? The most powerful natural explosion in recent Earth history occurred on 1908 June 30 when a meteor exploded above the Tunguska River in Siberia, Russia. Detonating with...

Gamma-Ray Burster
18.03.1997

What and where are the Gamma-Ray Bursters? Since their discovery in the early 1970s, nobody has been able to explain the cause of mysterious flashes of gamma rays that come from seemingly random directions on the sky.

Thackerays Globules
12.06.2012

These are larger dust bunnies than you will find under your bed. Situated in rich star fields and glowing hydrogen gas, these opaque clouds of interstellar dust and gas are so large they might be able to form stars.

Places for OSIRIS REx to Touch Asteroid Bennu
22.12.2019

Where is the best place to collect a surface sample from asteroid Bennu? Launched in 2016, NASA sent the robotic Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) to investigate the 500-meter-across asteroid 101955 Bennu.

Gamma Ray Bursts from the Unknown
27.08.1995

Gamma Ray Bursts (GRBs) pose one of the greatest mysteries of modern astronomy. About once a day, the gamma-ray sky lights up with a spectacular explosion. No one knows what causes these explosions or even how far away they are.

Young Star Cluster Westerlund 2
26.06.2010

Dusty stellar nursery RCW 49 surrounds young star cluster Westerlund 2 in this remarkable composite skyscape from beyond the visible spectrum of light. Infrared data from the Spitzer Space Telescope is shown in black...

The Hubble Ultra Deep Field in Light and Sound
1.08.2021

Have you heard about the Hubble Ultra-Deep Field? Either way, you've likely not heard about it like this -- please run your cursor over the featured image and listen! The Hubble Ultra-Deep Field (HUDF)...

Apollo Surveyor Stereo View
9.03.2001

Put on your red/blue glasses and gaze into this dramatic stereo view from the surface of the Moon! Inspired by last Saturday's APOD, Patrick Vantuyne offers this stereo rendering of the captivating picture of Apollo 12 astronaut Pete Conrad visiting the Surveyor